Among the on going quality problems that face most stamping facilities are those involved with the feeding of clean blanks into die sets so that the parts being struck or reformed are not blemished by foreign matter known as "dirt" often picked up by the blank from the transfer belt. Even minute particles of such dirt, i.e., metal flakes or shavings, grinding dust, paint chips and coatings, which are picked up by the blank being conveyed cause objectionable defects. This is particularly the case when such dirt finds its way between the sheet metal of the blank and the die surface and cause small blemishes or "pimples" to be formed on the part during the stamping process.
Such blemishes are generally very noticeable and are very objectionable defects that show through paint jobs subsequently applied to the stamped part. The painted surface often appear as pitted or roughened spots or areas on the finished part. These surface and paint defects lead to part rejection resulting in expensive refinishing or scrapping which materially adds to part costs and detracts from production efficiency.
To solve or substantially alleviate such problems, the present invention is drawn to new and improved mechanisms and methods for cleaning transfer belts on a continuous basis so that "dirt" will be eliminated from the belt before blank pick-up and the feed of the blank into a die set. With elimination of such dirt, contamination of the blanks by belt born dirt during blank conveyance on the belt is eliminated or sharply reduced.
More particularly, the invention is further drawn to a new and improved and compact transfer belt cleaning unit which in a preferred configuration, has a shell-like housing of two main components which when closed contains a cleaning or washing fluid manifold that directs sprays of washing fluid onto the belt to remove contaminants therefrom and which encloses and isolates sections of the belt as it feeds therethrough. The housing also contains mechanisms which collect metal particles and wipes dirt off of the belt moving therethrough on a continuous basis. In this invention, a magnet is advantageously employed to pick-up metal particles such as steel filings and flakes from the surface of the belt during cleaning operation.
This invention is still further drawn to a new and improved belt cleaning method that significantly reduces the amount of "dirt" previously transmitted from the belt onto a metal blank being transferred into stamping dies and then between the die and the metal blank to thereby prevent the stamping of parts having a wide range of dirt induced deformations or imperfections in the surfaces thereof.
In a preferred embodiment of the washer unit of invention, a top or box-like upper support frame contains a belt entry back-up roller, a belt deflector plate, a squeegee back-up roller, and a back-up belt exit roller. All rollers may be mounted on needle roller bearings to reduce friction on the belt during belt start and stop cycles. The belt deflector plate backs up the belt above the washing fluid sprayers and the magnets to stabilize the belt from spray induced vibration as well as other causes prior to "squeegee" or belt wiping action. The squeegee back-up roller is located directly above the squeegee blade and maintains a position which reduces friction and provides a backing or reaction for the pressure loads needed by the squeegee blades to mechanically wipe dirt particles as well as the belt wash fluid off the belt. The back-up entry and exit rollers are disposed against the top of the belt and spring biased entrance and exit belt support rollers in a lower body align with the corresponding back-up entry and exit roller to act as fluid seals to help keep the belt wash fluid inside the washer unit.
The main body of the unit which mounts to the top frame by a side hinge system and can be swung out of the way to simplify belt access and belt replacement when necessary. There are spaced side anchor points fixed toward the front of the housing as provided by the upper frame and main body that releasably secure these two parts together for normal belt cleaning operation.
A floating belt supporting entrance roller is mounted by a spring and gibb guide system in the main housing that provides for varying belt thicknesses and that materially aids in keeping the wash cavity of the main housing sealed. A wash spray manifold mounted in the cavity of the main housing distributes streams of pressurized water and detergents or other cleaning fluid directly onto the belt with high velocity from a plurality of laterally spaced nozzles. The spray impacts the dirt across the entire width of the belt and flushes such material therefrom. The spray also dilutes the built up of any belt wash concentrate or other materials still adhering thereto to augment subsequent cleaning by the wiping blade of the squeegee.
The lower main body also has a belt supporting exit roller mounted on a floating spring gibb system that seals the cavity of the unit while adjustably accommodating various belt thicknesses. There are two splash baffles mounted internally in the lower housing that prevent excess fluid from flooding the entrance and exit rollers. A pipe nipple welded or otherwise mounted into the floor of the main body serves as a connection for a fluid drain pipe leading back to a reservoir. A fluid inlet fitting welded into a side wall of the main body connects to the spray manifold to provide a connection to a flexible fluid supply line between a hard pipe system feeding the cleaning fluid to the cleaning unit.
There are two slide rails mounted inside the cavity of the lower main body that support and guide the removable squeegee and magnet support module.
The slide module of this invention permits the ready removal of the entire squeegee and magnet system from the main body. This new system allows remote bench repair of module mounted components instead of working in the confined framework of the presses and the conveyor.
The slide system for the module may consist of two extrusions that form runners which slidably fit on the cylindrical and parallel slide rails. The runners fit on and encapsulates most of the circumference of the rails so that the module is held in the main body by this sliding connection until axially removed therefrom. The rails are fixed to the floor of the main body by small diameter pedestals.
A face plate mounted to one outer end of the extrusions that serve as a closure and splash guard for the lower unit frame or main body. There is an outer handle that is operatively mounted to the face plate that serves as both a manual grip for axial movement of the module relative to the housing and an indicator that shows the amount of wear on the rubber-like material of the squeegee blades. The handle turns by action of a spring mechanism on the structure holding the squeegee blade on the belt and acts as a pointer on fixed indicia on the face plate to provide a squeegee wear detecting gauge.
The module has two main mounting plates rigidly attached to the upper surface of the extrusions that serve as supports for a pair of laterally-spaced uprights having a laterally extending magnet support tray mounted to the upper ends thereof and for a squeegee support and linkage system. Permanent magnets are mounted in the support tray that fastens to the top of the uprights so that they are immediately below the face of the belt. The uprights rigidly secured to the mounting plates and which extend upwardly therefrom provide the pivot support for the squeegee support linkage and squeegee assembly.
The squeegee assembly comprises an elongated body with a plurality of elongated blades of rubber or rubber-like material arcuately spaced from one another. The squeegee body can accordingly be indexed four times so that four different squeegee blades can be used to extend production hours with minimal preventive maintenance time. When one squeegee cartridge or assembly with four radial blades is worn out, it can be readily removed and a new squeegee cartridge preferably corresponding to the old one can be readily substituted therefor. The squeegee to belt pressure is provided by springs captured between the mounting plates and the outer ends of the spaced arms of the squeegee link gage. The squeegee cartridge is manually turned so that its operative blade is located directly below a squeegee back-up roller mounted in the upper frame when the unit is in operation.
These and other features, objects and advantages of the invention will become more apparent from the following detailed drawings and description in which: